Immunotherapeutic synergy between anti-CD137 mAb and intratumoral administration of a cytopathic Semliki Forest virus encoding IL-12

Intratumoral injection of Semliki Forest virus encoding interleukin-12 (SFV-IL-12) combines acute expression of IL-12 and stressful apoptosis of infected malignant cells. Agonist antibodies directed to costimulatory receptor CD137 (4-1BB) strongly amplify pre-existing cellular immune responses toward weak tumor antigens. In this study, we provide evidence for powerful synergistic effects of a combined strategy consisting of intratumoral injection of SFV-IL-12 and systemic delivery of agonist anti-CD137 monoclonal antibodies (mAbs), which was substantiated against poorly immunogenic B16 melanomas (B16-OVA and B16.F10) and TC-1 lung carcinomas. Effector CD8(β)(+) T cells were sufficient to mediate complete tumor eradications. Accordingly, there was an intensely synergistic in vivo enhancement of cytotoxic T lymphocytes (CTL)-mediated immunity against the tumor antigens OVA and tyrosine-related protein-2 (TRP-2). This train of phenomena led to long-lasting tumor-specific immunity against rechallenge, attained transient control of the progression of concomitant tumor lesions that were not directly treated with SFV-IL-12 and caused autoimmune vitiligo. Importantly, we found that SFV-IL-12 intratumoral injection induces bright expression of CD137 on most tumor-infiltrating CD8(+) T lymphocytes, thereby providing more abundant targets for the action of the agonist antibody. This efficacious combinatorial immunotherapy strategy offers feasibility for clinical translation since anti-CD137 mAbs are already undergoing clinical trials and development of clinical-grade SFV-IL-12 vectors is in progress

Células dendríticas especializadas en presentación de antígenos exógenos a linfocitos T citotóxicos

Dendritic cells (DC) are cells of hematopoietic origin, which constitutively express MHC class I and II, and are functionally the most potent inducers of T-lymphocyte activation and proliferation. CD8+ T lymphocytes proliferate and acquire cytotoxic functions upon recognition of their cognate antigen on the surface of one or various dendritic cells with which they interact. However, only some DC subsets are able to present antigen to cytotoxic T cell precursors as taken up from extracellular sources. This function is termed cross-presentation (in Spanish, presentación cruzada or presentación subrogada) and requires shuttle mechanisms from phagosomes to the cytosol for antigen processing. It has been demonstrated that the differentiation of DC with these capabilities is dependent on FLT-3L and the transcription factor BATF3. They express peculiar functions and differentiation markers. These cells are distinguished in mice by surface CD8 features, while CD141 (BDCA-3) marks these cells in the human. These subpopulations are capable of selective internalization of necrotic cell debris by means of their CLEC9A lectin which is a receptor for extracellular polymerized actin. Expression of the chemokine receptor XCR1 favours contact with CD8+ T cells. Therapeutic vaccination with tumour antigens using DC is a strategy under development for the treatment of cancer. The use of DC subsets with more prominent capabilities for cross-presentation would mimic the natural mechanisms of immunization to induce cytolitic T lymphocytes. In vivo targeting of antigens with monoclonal antibodies against DEC-205 or CLEC9A attains very robust immune responses and is a strategy undergoing clinical trials for chronic viral diseases and malignancies

Endoscopical and pathological dissociation in severe colitis induced by immune-checkpoint inhibitors

Checkpoint inhibitors have improved the survival of patients with advanced tumors and show a manageable toxicity profile. However, auto-immune colitis remains a relevant side effect, and combinations of anti-PD1/PDL1 and anti-CTLA-4 increase its incidence and severity. Here, we report the case of a 50-year-old patient diagnosed with stage IV cervical cancer that relapsed following radical surgery, external radiation/brachytherapy and standard chemotherapy. She was subsequently treated with Nivolumab and Ipilimumab combination and developed grade 2 colitis presenting a dissociation between endoscopic and pathological findings. At cycle 10 the patient reported grade 3 diarrhea and abdominal discomfort, without blood or mucus in the stools. Immunotherapy was withheld and a colonoscopy was performed, showing normal mucosa in the entire colon. Puzzlingly, histologic evaluation of randomly sampled mucosal biopsy of the distal colon showed an intense intraepithelial lymphocyte infiltration with crypt loss and some regenerating crypts with a few apoptotic bodies set in a chronically inflamed lamina propria, consistent with the microscopic diagnosis of colitis. Treatment with methylprednisolone 2 mg/kg was initiated which led to a decrease in the number of stools to grade 1. Additional investigations to exclude other causes of diarrhea rendered negative results. The patient experienced a major partial response and, following the resolution of diarrhea, she was re-challenged again with immunotherapy, with the reappearance of grade 2 diarrhea, leading to permanent immunotherapy interruption. We conclude and propose that performing random colonic biopsies should be considered in cases of immune checkpoint-associated unexplained diarrhea, even when colonoscopy shows macroscopically normal colonic mucosa inflammatory lesions

Cytokines in clinical cancer immunotherapy

Cytokines are soluble proteins that mediate cell-to-cell communication. Based on the discovery of the potent anti-tumour activities of several pro-inflammatory cytokines in animal models, clinical research led to the approval of recombinant interferon-alpha and interleukin-2 for the treatment of several malignancies, even if efficacy was only modest. These early milestones in immunotherapy have been followed by the recent addition to clinical practice of antibodies that inhibit immune checkpoints, as well as chimeric antigen receptor T cells. A renewed interest in the anti-tumour properties of cytokines has led to an exponential increase in the number of clinical trials that explore the safety and efficacy of cytokine-based drugs, not only as single agents, but also in combination with other immunomodulatory drugs. These second-generation drugs under clinical development include known molecules with novel mechanisms of action, new targets, and fusion proteins that increase half-life and target cytokine activity to the tumour microenvironment or to the desired effector immune cells. In addition, the detrimental activity of immunosuppressive cytokines can be blocked by antagonistic antibodies, small molecules, cytokine traps or siRNAs. In this review, we provide an overview of the novel trends in the cytokine immunotherapy field that are yielding therapeutic agents for clinical trials

Daratumumab in combination with urelumab to potentiate anti-myeloma activity in lymphocytedeficient mice reconstituted with human NK cells

Daratumumab is an anti-CD38 fully human IgG1 mAb approved for multiple myeloma treatment. One of the proposed mechanisms of action is the induction of antibody-dependent cellular cytotoxicity (ADCC) mediated by NK cells. NK cells acquire surface CD137 expression in the presence of solid-phase-attached daratumumab and when encountering a daratumumab-coated CD38+ tumor cell line. In this setting, addition of the agonist anti-CD137 mAb urelumab enhances NK-cell activation increasing CD25 expression and IFNɣ production. However, in vitro ADCC is not increased by the addition of urelumab both in 4h or 24h lasting experiments. To study urelumab-increased daratumumab-mediated ADCC activity in vivo, we set up a mouse model based on the intravenous administration of a luciferase-transfected multiple myeloma cell line of human origin, human NK cells and daratumumab to immuno-deficient NSG mice. In this model, intravenous administration of urelumab 24h after daratumumab delayed tumor growth and prolonged mice survival

PSA reactivity in extracellular microvesicles to commercial immunoassays

Aims: Characterization of PSA in extracellular microvesicles (EVs) and its reactivity to commercial methods. Materials and methods: EVs derived from serum of 47 prostate cancer (PCa) patients, 27 benign prostatic hyperplasia (BPH) patients and 42 healthy controls were analyzed. EVs isolation and quantification of PSA immunoreactive to total (ev-T-PSA) or free (ev-F-PSA) PSA immunoassays, were performed using commercial assays. PSA in CD81+ or CD63+ EVs was determined directly in serum by an immunocapture-ELISA (IC-ELISA). Results: Ev-T-PSA immunoreactive to Elecsys assay was detected in all samples. Median T-PSA ev/srm ratio was 2.20 % (Q1-Q3: 0.80-4.00 %), although in some samples this ratio reached 59 %. T-PSA ev/srm ratio was higher in those samples with serum T-PSA below 4 µg/L than in those exceeding that cut-off (p < 0.001). T-PSA ev/srm ratio was lower in PCa patients compared to healthy controls and BPH patients (p < 0.001). Elecsys immunoassays detected higher concentrations of ev-T-PSA and ev-F-PSA than Immulite (p < 0.001). PSA was detected by IC-ELISA more intensely in CD81+ EVs than in CD63+ EVs, and ev-T-PSA correlated with PSA+ CD63+ (p < 0.001) but not with PSA+ CD81+. Conclusion: EVs-bound PSA is another form of circulating PSA whose measurement could be easily performed in clinical laboratories by automated immunoassays

Heterogenous presence of neutrophil extracellular traps in human solid tumours is partially dependent on IL-8

Neutrophil extracellular traps (NETs) are webs of extracellular nuclear DNA extruded by dying neutrophils infiltrating tissue. NETs constitute a defence mechanism to entrap and kill fungi and bacteria. Tumours induce the formation of NETs to the advantage of the malignancy via a variety of mechanisms shown in mouse models. Here, we investigated the presence of NETs in a variety of human solid tumours and their association with IL-8 (CXCL8) protein expression and CD8+ T-cell density in the tumour microenvironment. Multiplex immunofluorescence panels were developed to identify NETs in human cancer tissues by co-staining with the granulocyte marker CD15, the neutrophil marker myeloperoxidase and citrullinated histone H3 (H3Cit), as well as IL-8 protein and CD8+ T cells. Three ELISA methods to detect and quantify circulating NETs in serum were optimised and utilised. Whole tumour sections and tissue microarrays from patients with non-small cell lung cancer (NSCLC; n = 14), bladder cancer (n = 14), melanoma (n = 11), breast cancer (n = 31), colorectal cancer (n = 20) and mesothelioma (n = 61) were studied. Also, serum samples collected retrospectively from patients with metastatic melanoma (n = 12) and NSCLC (n = 34) were ELISA assayed to quantify circulating NETs and IL-8. NETs were detected in six different human cancer types with wide individual variation in terms of tissue density and distribution. At least in NSCLC, bladder cancer and metastatic melanoma, NET density positively correlated with IL-8 protein expression and inversely correlated with CD8+ T-cell densities. In a series of serum samples from melanoma and NSCLC patients, a positive correlation between circulating NETs and IL-8 was found. In conclusion, NETs are detectable in formalin-fixed human biopsy samples from solid tumours and in the circulation of cancer patients with a considerable degree of individual variation. NETs show a positive association with IL-8 and a trend towards a negative association with CD8+ tumour-infiltrating lymphocytes

Genomic characterization of individuals presenting extreme phenotypes of high and low risk to develop tobacco-induced lung cancer

Single nucleotide polymorphisms (SNPs) may modulate individual susceptibility to carcinogens. We designed a genome-wide association study to characterize individuals presenting extreme phenotypes of high and low risk to develop tobacco-induced non-small cell lung cancer (NSCLC), and we validated our results. We hypothesized that this strategy would enrich the frequencies of the alleles that contribute to the observed traits. We genotyped 2.37 million SNPs in 95 extreme phenotype individuals, that is: heavy smokers that either developed NSCLC at an early age (extreme cases); or did not present NSCLC at an advanced age (extreme controls), selected from a discovery set (n=3631). We validated significant SNPs in 133 additional subjects with extreme phenotypes selected from databases including >39,000 individuals. Two SNPs were validated: rs12660420 (p(combined)=5.66x10(-5); ORcombined=2.80), mapping to a noncoding transcript exon of PDE10A; and rs6835978 (p(combined)=1.02x10(-4); ORcombined=2.57), an intronic variant in ATP10D. We assessed the relevance of both proteins in early-stage NSCLC. PDE10A and ATP10D mRNA expressions correlated with survival in 821 stage I-II NSCLC patients (p=0.01 and p<0.0001). PDE10A protein expression correlated with survival in 149 patients with stage I-II NSCLC (p=0.002). In conclusion, we validated two variants associated with extreme phenotypes of high and low risk of developing tobacco-induced NSCLC. Our findings may allow to identify individuals presenting high and low risk to develop tobacco-induced NSCLC and to characterize molecular mechanisms of carcinogenesis and resistance to develop NSCLC

Neoadjuvant immunotherapy in non-small cell lung cancer: the sooner the better?

Recently, Forde et al. reported in the New England Journal of Medicine a pilot study in which two neoadjuvant doses of the PD-1 inhibitor nivolumab were administered in a preoperative fashion to 21 patients with untreated, surgically resectable early (stage I–IIIA) non-small cell lung cancer (NSCLC) (1). Surgery was performed 4 weeks after the first dose of nivolumab. In addition to an acceptable toxicity profile, which did not cause delays in surgery, nivolumab induced a major pathological response in 9 of 20 resected tumors (45%). Pathological responses were observed in patients presenting PD-L1 positive and negative tumors and, interestingly, they correlated with pretreatment tumor mutational burden. The authors found that the number of T-cell clones observed in the tumor and peripheral blood increased following nivolumab in eight of nine patients. Remarkably, the authors described one patient presenting a complete response in which neoantigen-specific T-cell clones from the primary tumor rapidly expanded in peripheral blood following treatment. Moreover, some of these clones were not detected before treatment with nivolumab, thus suggesting that PD-1 blockade induced their expansion

Células dendríticas especializadas en presentación de antígenos exógenos a linfocitos T citotóxicos

Dendritic cells (DC) are cells of hematopoietic origin, which constitutively express MHC class I and II, and are functionally the most potent inducers of T-lymphocyte activation and proliferation. CD8+ T lymphocytes proliferate and acquire cytotoxic functions upon recognition of their cognate antigen on the surface of one or various dendritic cells with which they interact. However, only some DC subsets are able to present antigen to cytotoxic T cell precursors as taken up from extracellular sources. This function is termed cross-presentation (in Spanish, presentación cruzada or presentación subrogada) and requires shuttle mechanisms from phagosomes to the cytosol for antigen processing. It has been demonstrated that the differentiation of DC with these capabilities is dependent on FLT-3L and the transcription factor BATF3. They express peculiar functions and differentiation markers. These cells are distinguished in mice by surface CD8 features, while CD141 (BDCA-3) marks these cells in the human. These subpopulations are capable of selective internalization of necrotic cell debris by means of their CLEC9A lectin which is a receptor for extracellular polymerized actin. Expression of the chemokine receptor XCR1 favours contact with CD8+ T cells. Therapeutic vaccination with tumour antigens using DC is a strategy under development for the treatment of cancer. The use of DC subsets with more prominent capabilities for cross-presentation would mimic the natural mechanisms of immunization to induce cytolitic T lymphocytes. In vivo targeting of antigens with monoclonal antibodies against DEC-205 or CLEC9A attains very robust immune responses and is a strategy undergoing clinical trials for chronic viral diseases and malignancies